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FIX/SBE - OSI layer 6 presentation for encoding and decoding application messages in binary format for low-latency applications.

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/*
 * Copyright 2013-2024 Real Logic Limited.
 * Copyright 2017 MarketFactory Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package uk.co.real_logic.sbe.xml;

import org.agrona.Strings;
import org.agrona.collections.ObjectHashSet;
import org.w3c.dom.*;
import org.xml.sax.InputSource;
import uk.co.real_logic.sbe.ValidationUtil;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.validation.SchemaFactory;
import javax.xml.xpath.*;
import java.io.File;
import java.io.InputStream;
import java.nio.ByteOrder;
import java.util.HashMap;
import java.util.Map;

import static uk.co.real_logic.sbe.PrimitiveType.*;
import static uk.co.real_logic.sbe.xml.Presence.REQUIRED;

/**
 * Encapsulate the XML Schema parsing for SBE so that other representations may be
 * used to generate independent representations.
 */
public class XmlSchemaParser
{
    /**
     * Key for storing {@link ErrorHandler} as user data in XML document.
     */
    public static final String ERROR_HANDLER_KEY = "SbeErrorHandler";

    static final String TYPE_XPATH_EXPR =
        "/*[local-name() = 'messageSchema']/types/" + EncodedDataType.ENCODED_DATA_TYPE;

    static final String COMPOSITE_XPATH_EXPR =
        "/*[local-name() = 'messageSchema']/types/" + CompositeType.COMPOSITE_TYPE;

    static final String ENUM_XPATH_EXPR =
        "/*[local-name() = 'messageSchema']/types/" + EnumType.ENUM_TYPE;

    static final String SET_XPATH_EXPR =
        "/*[local-name() = 'messageSchema']/types/" + SetType.SET_TYPE;

    static final String MESSAGE_SCHEMA_XPATH_EXPR =
        "/*[local-name() = 'messageSchema']";

    static final String MESSAGE_XPATH_EXPR =
        "/*[local-name() = 'messageSchema']/*[local-name() = 'message']";

    /**
     * Validate the document against a given schema. Errors will be written to {@link java.lang.System#err}.
     *
     * @param xsdFilename schema to validate against.
     * @param is          source from which schema is read. Ideally it will have the systemId property set to resolve
     *                    relative references.
     * @param options     to be applied during parsing.
     * @throws Exception if an error occurs when parsing the document or schema.
     */
    public static void validate(final String xsdFilename, final InputSource is, final ParserOptions options)
        throws Exception
    {
        final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        final SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);

        factory.setSchema(schemaFactory.newSchema(new File(xsdFilename)));
        factory.setNamespaceAware(true);

        if (options.xIncludeAware())
        {
            factory.setXIncludeAware(true);
            factory.setFeature("http://apache.org/xml/features/xinclude/fixup-base-uris", false);
        }

        factory.newDocumentBuilder().parse(is);
    }

    /**
     * Wraps the {@link InputStream} into an {@link InputSource} and delegates to
     * {@link #validate(String, InputSource, ParserOptions)}.
     * 

* Note: this method does not set the {@link InputSource#setSystemId(java.lang.String)} property. * However, it is recommended to use the {@link #validate(String, InputSource, ParserOptions)} method directly. * * @param xsdFilename schema to validate against. * @param in document to be validated. * @param options to be applied during parsing. * @throws Exception if an error occurs when parsing the document or schema. */ public static void validate(final String xsdFilename, final InputStream in, final ParserOptions options) throws Exception { validate(xsdFilename, new InputSource(in), options); } /** * Take an {@link InputSource} and parse it generating map of template ID to Message objects, types, and schema. * * @param is source from which schema is read. Ideally it will have the systemId property set to resolve * relative references. * @param options to be applied during parsing. * @return {@link MessageSchema} encoding for the schema. * @throws Exception on parsing error. */ public static MessageSchema parse(final InputSource is, final ParserOptions options) throws Exception { final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); if (options.xIncludeAware()) { factory.setNamespaceAware(true); factory.setXIncludeAware(true); factory.setFeature("http://apache.org/xml/features/xinclude/fixup-base-uris", false); } final Document document = factory.newDocumentBuilder().parse(is); final ErrorHandler errorHandler = new ErrorHandler(options); document.setUserData(ERROR_HANDLER_KEY, errorHandler, null); final XPath xPath = XPathFactory.newInstance().newXPath(); final Map typeByNameMap = findTypes(document, xPath); errorHandler.checkIfShouldExit(); final Map messageByIdMap = findMessages(document, xPath, typeByNameMap); errorHandler.checkIfShouldExit(); final Node schemaNode = (Node)xPath.compile(MESSAGE_SCHEMA_XPATH_EXPR).evaluate(document, XPathConstants.NODE); if (null == schemaNode) { throw new IllegalStateException("messageSchema element not found in document, schema is not valid for SBE"); } final MessageSchema messageSchema = new MessageSchema(schemaNode, typeByNameMap, messageByIdMap); messageSchema.validate(errorHandler); errorHandler.checkIfShouldExit(); return messageSchema; } /** * Wraps the {@link InputStream} into an {@link InputSource} and delegates to * {@link #parse(InputSource, ParserOptions)}. *

* Note: this method does not set the {@link InputSource#setSystemId(java.lang.String)} property. * However, it is recommended to use the {@link #parse(InputSource, ParserOptions)} method directly. * * @param in stream from which schema is read. * @param options to be applied during parsing. * @return {@link MessageSchema} encoding for the schema. * @throws Exception on parsing error. */ public static MessageSchema parse(final InputStream in, final ParserOptions options) throws Exception { return parse(new InputSource(in), options); } /** * Scan XML for all types (encodedDataType, compositeType, enumType, and setType) and save in a map. * * @param document for the XML parsing. * @param xPath for XPath expression reuse. * @return {@link java.util.Map} of name {@link java.lang.String} to {@link Type}. * @throws XPathExpressionException on parsing error. */ public static Map findTypes(final Document document, final XPath xPath) throws XPathExpressionException { final Map typeByNameMap = new HashMap<>(); typeByNameMap.put("char", new EncodedDataType("char", REQUIRED, null, null, CHAR, 1, false)); typeByNameMap.put("int8", new EncodedDataType("int8", REQUIRED, null, null, INT8, 1, false)); typeByNameMap.put("int16", new EncodedDataType("int16", REQUIRED, null, null, INT16, 1, false)); typeByNameMap.put("int32", new EncodedDataType("int32", REQUIRED, null, null, INT32, 1, false)); typeByNameMap.put("int64", new EncodedDataType("int64", REQUIRED, null, null, INT64, 1, false)); typeByNameMap.put("uint8", new EncodedDataType("uint8", REQUIRED, null, null, UINT8, 1, false)); typeByNameMap.put("uint16", new EncodedDataType("uint16", REQUIRED, null, null, UINT16, 1, false)); typeByNameMap.put("uint32", new EncodedDataType("uint32", REQUIRED, null, null, UINT32, 1, false)); typeByNameMap.put("uint64", new EncodedDataType("uint64", REQUIRED, null, null, UINT64, 1, false)); typeByNameMap.put("float", new EncodedDataType("float", REQUIRED, null, null, FLOAT, 1, false)); typeByNameMap.put("double", new EncodedDataType("double", REQUIRED, null, null, DOUBLE, 1, false)); forEach( (NodeList)xPath.compile(TYPE_XPATH_EXPR).evaluate(document, XPathConstants.NODESET), (node) -> addTypeWithNameCheck(typeByNameMap, new EncodedDataType(node), node)); forEach( (NodeList)xPath.compile(COMPOSITE_XPATH_EXPR).evaluate(document, XPathConstants.NODESET), (node) -> addTypeWithNameCheck(typeByNameMap, new CompositeType(node), node)); forEach( (NodeList)xPath.compile(ENUM_XPATH_EXPR).evaluate(document, XPathConstants.NODESET), (node) -> addTypeWithNameCheck(typeByNameMap, new EnumType(node), node)); forEach( (NodeList)xPath.compile(SET_XPATH_EXPR).evaluate(document, XPathConstants.NODESET), (node) -> addTypeWithNameCheck(typeByNameMap, new SetType(node), node)); return typeByNameMap; } /** * Scan XML for all message definitions and save in map. * * @param document for the XML parsing. * @param xPath for XPath expression reuse. * @param typeByNameMap to use for Type objects. * @return {@link java.util.Map} of schemaId to {@link Message}. * @throws XPathExpressionException on parsing error. */ public static Map findMessages( final Document document, final XPath xPath, final Map typeByNameMap) throws XPathExpressionException { final Map messageByIdMap = new HashMap<>(); final ObjectHashSet distinctNames = new ObjectHashSet<>(); forEach( (NodeList)xPath.compile(MESSAGE_XPATH_EXPR).evaluate(document, XPathConstants.NODESET), (node) -> addMessageWithIdCheck(distinctNames, messageByIdMap, new Message(node, typeByNameMap), node)); if (messageByIdMap.isEmpty()) { handleWarning(document.getDocumentElement(), "no messages found in document"); } return messageByIdMap; } /** * Handle an error condition as consequence of parsing. * * @param node that is the context of the warning. * @param msg associated with the error. */ public static void handleError(final Node node, final String msg) { final ErrorHandler handler = (ErrorHandler)node.getOwnerDocument().getUserData(ERROR_HANDLER_KEY); if (null == handler) { throw new IllegalStateException("ERROR: " + formatLocationInfo(node) + msg); } else { handler.error(formatLocationInfo(node) + msg); } } /** * Handle a warning condition as a consequence of parsing. * * @param node as the context for the warning. * @param msg associated with the warning. */ public static void handleWarning(final Node node, final String msg) { final ErrorHandler handler = (ErrorHandler)node.getOwnerDocument().getUserData(ERROR_HANDLER_KEY); if (null == handler) { throw new IllegalStateException("WARNING: " + formatLocationInfo(node) + msg); } else { handler.warning(formatLocationInfo(node) + msg); } } /** * Helper function that throws an exception when the attribute is not set. * * @param elementNode that should have the attribute. * @param attrName that is to be looked up. * @return value of the attribute. * @throws IllegalStateException if the attribute is not present. */ public static String getAttributeValue(final Node elementNode, final String attrName) { if (null == elementNode) { throw new IllegalStateException( "element node is null when looking for attribute: " + attrName); } final NamedNodeMap attributes = elementNode.getAttributes(); final Node attrNode = attributes.getNamedItemNS(null, attrName); if (null == attrNode) { throw new IllegalStateException( "element '" + elementNode.getNodeName() + "' has missing attribute: " + attrName); } final String nodeValue = attrNode.getNodeValue(); if (Strings.isEmpty(nodeValue)) { throw new IllegalStateException( "element '" + elementNode.getNodeName() + "' has empty attribute: " + attrName); } return nodeValue; } /** * Helper function that uses a default value when value not set. * * @param elementNode that should have the attribute. * @param attrName that is to be looked up. * @param defValue value to return if not set. * @return value of the attribute or defValue. */ public static String getAttributeValue(final Node elementNode, final String attrName, final String defValue) { if (null == elementNode) { throw new IllegalStateException( "element node is null when looking for attribute: " + attrName); } final NamedNodeMap attributes = elementNode.getAttributes(); final Node attrNode = attributes.getNamedItemNS(null, attrName); if (null == attrNode) { return defValue; } return attrNode.getNodeValue(); } /** * To be used with descendant elements of {@code } elements. Returns the package attribute value as * defined on the ancestor {@code } element. * * @param elementNode the node inside the {@code } element. * @return the package name, or null if not defined. */ public static String getTypesPackageAttribute(final Node elementNode) { Node parentNode = elementNode.getParentNode(); while (null != parentNode) { if ("types".equals(parentNode.getLocalName()) || "types".equals(parentNode.getNodeName())) { return getAttributeValue(parentNode, "package", null); } parentNode = parentNode.getParentNode(); } return null; } /** * Helper function that hides the null return from {@link org.w3c.dom.NamedNodeMap#getNamedItem(String)}. * * @param elementNode that could be null. * @param attrName that is to be looked up. * @return null or value of the attribute. */ public static String getAttributeValueOrNull(final Node elementNode, final String attrName) { if (null == elementNode) { return null; } final NamedNodeMap attributes = elementNode.getAttributes(); if (null == attributes) { return null; } final Node attrNode = attributes.getNamedItemNS(null, attrName); if (null == attrNode) { return null; } return attrNode.getNodeValue(); } /** * Helper function to convert a schema byteOrderName into a {@link ByteOrder}. * * @param byteOrderName specified as a FIX SBE string. * @return ByteOrder representation. */ public static ByteOrder getByteOrder(final String byteOrderName) { if ("bigEndian".equals(byteOrderName)) { return ByteOrder.BIG_ENDIAN; } return ByteOrder.LITTLE_ENDIAN; } /** * Check name against validity for C++ and Java naming. Warning if not valid. * * @param node to have the name checked. * @param name of the node to be checked. */ public static void checkForValidName(final Node node, final String name) { if (!ValidationUtil.isSbeCppName(name)) { handleWarning(node, "name is not valid for C++: " + name); } if (!ValidationUtil.isSbeJavaName(name)) { handleWarning(node, "name is not valid for Java: " + name); } if (!ValidationUtil.isSbeGolangName(name)) { handleWarning(node, "name is not valid for Golang: " + name); } if (!ValidationUtil.isSbeCSharpName(name)) { handleWarning(node, "name is not valid for C#: " + name); } } private static void addTypeWithNameCheck(final Map typeByNameMap, final Type type, final Node node) { if (typeByNameMap.get(type.name()) != null) { handleWarning(node, "type already exists for name: " + type.name()); } checkForValidName(node, type.name()); typeByNameMap.put(type.name(), type); } private static void addMessageWithIdCheck( final ObjectHashSet distinctNames, final Map messageByIdMap, final Message message, final Node node) { if (messageByIdMap.get((long)message.id()) != null) { handleError(node, "message template id already exists: " + message.id()); } if (!distinctNames.add(message.name())) { handleError(node, "message name already exists: " + message.name()); } checkForValidName(node, message.name()); messageByIdMap.put((long)message.id(), message); } private static String formatLocationInfo(final Node node) { final Node parentNode = node.getParentNode(); return "at " + "<" + parentNode.getNodeName() + (getAttributeValueOrNull(parentNode, "name") == null ? ">" : (" name=\"" + getAttributeValueOrNull(parentNode, "name") + "\"> ")) + "<" + node.getNodeName() + (getAttributeValueOrNull(node, "name") == null ? ">" : (" name=\"" + getAttributeValueOrNull(node, "name") + "\"> ")); } @FunctionalInterface interface NodeFunction { void execute(Node node) throws XPathExpressionException; } static void forEach(final NodeList nodeList, final NodeFunction func) throws XPathExpressionException { for (int i = 0, size = nodeList.getLength(); i < size; i++) { func.execute(nodeList.item(i)); } } }





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